Vaginal dryness affects about 50% of postmenopausal women at the age of 50 to 60 years and 72% after 70 years (Rossin-Amar, 2000, Gynecol Obstet Fertil, 28(3): 245-249). Of these women, about 80% experience urogenital disorders, especially vaginitis and dyspareunia (Pandit and Ouslander, 1997, Am J Med Sci, 314(4): 228-31). Since these problems are believed to be at least partially related to a deprivation of sex steroids, appropriate local hormonal replacement therapy should be considered at menopause. It has recently been recognized that postmenopausal women are not only deprived of all ovarian estrogens but they are also progressively deprived of the androgens originating from the peripheral intracrine transformation of dehydroepiandrosterone (DHEA) into both androgens and estrogens (Labrie et al., 1991, Mol Cell Endocrinol, 78: C113-C118; Labrie et al., 1995, Ann NY Acad Sci, 774: 16-28; Labrie et al., 2003, End Rev, 24(2): 152-182). In fact, serum DHEA and DHEA-S progressively decrease from the age of 30 to 40 years (Labrie et al., 2003, End Rev, 24(2): 152-182; Orentreich et al., 1984, J Clin Endocrinol Metab, 59: 551-555; Labrie et al., 1997, J Clin Endocrinol Metab, 82: 2396-2402). A series of studies indicate that low levels of DHEA and DHEA-S are associated with a series of age-related morbidity and diseases (Labrie et al., 1997, J. Clin. Endocrinol. Metab., 82: 3498-3505; Helzlsouer et al., 1992, Cancer Res, 52(1): 1-4; Szathmari et al., 1994, Osteoporos Int, 4(2): 84-88; Thoman and Weigle, 1989, Adv Immununol, 46: 221-261; Barrett-Connor et al., 1999, J Reprod Med, 44(12): 1012-1020; Barrett-Connor et al., 1999, J Am Geriatr Soc, 47(6): 685-691).
An efficient approach to alleviate vaginal dryness and other menopausal symptoms is the use of hormone replacement therapy (HRT) (Greendale and Judd, 1993, J Am Geriatr Soc, 41(4): 426-436; Studd et al., 1980, Pasetto, Paleotti and Ambrus Eds, M T Press, Lancaster, p: 127-139). Recent clinical studies, however, have indicated that combining estrogens and progestins increases the incidence of breast cancer with a potential negative impact on cardiovascular events (Colditz et al., 1995, N Engl J Med, 332: 1589-1593; Ross et al., 2000, J Natl Cancer Inst, 92(4): 328-332; Rossouw et al., 2002, JAMA, 288(3): 321-333). Meanwhile, there is an increasing interest in the potential of combined estrogen-androgen replacement therapy (Rosenberg et al., 1997, J Reprod Med, 42(7): 394-404; Burd et al., 2001, Curr Women Health Rep, 1(3):202-205), although the use of the estrogenic component is limited by the potential complications mentioned above. Based upon recent advances in our understanding of human sex steroid physiology, especially in postmenopausal women (Labrie et al., 1991, Mol Cell Endocrinol, 78: C113-C118; Labrie et al., 2003, End Rev, 24(2): 152-182), the use of DHEA becomes a possibility to provide postmenopausal women with the appropriate levels of androgens and estrogens synthesised in specific tissues by intracrine mechanisms, with no systemic effects (Labrie et al., 1997, J. Clin. Endocrinol. Metab., 82: 3498-3505: 16-28; Labrie et al., 2003, End Rev, 24(2): 152-182; Labrie, 2001, Ref Gyn Obstet, 8: 317-322; Lasco et al., 2002, 145: 457-461). The restauration of androgen-sensitive elements of vaginal function should also help the action of inhibitors of type 5 cGMP phosphodiesterase or prostaglandin E1.
The selective estrogen receptor modulator (SERM) Acolbifene (EM-652) is a benzopyran derivative originally developed for the prevention and treatment of breast cancer (Gauthier et al., 1997, J Med Chem, 40: 2117-2122). Acolbifene is the compound having the highest affinity of all known compounds for the ER (Gauthier et al., 1997, J Med Chem, 40: 2117-2122; Labrie et al., 1999, J Steroid Biochem Mol Biol, 69 (1-6): 51-84; Tremblay et al., 1997, Mol. Endocrinol., 11: 353-365) and it exerts its activity on both ERα and ERβ (Tremblay et al., 1998, Endocrinology, 139: 111-118). This compound displays a pure and highly potent antiestrogenic activity in the mammary gland and endometrium while decreasing serum cholesterol and triglycerides and preventing bone loss, at least in the rat (Labrie et al., 1999, J Steroid Biochem Mol Biol, 69 (1-6): 51-84). Moreover, it has been demonstrated that the administration of DHEA, not only does not interfere, but does exert an additive inhibitory effect with the pure antiestrogen Acolbifene on human breast tumour growth in the nude mouse (Dauvois et al., 1991, Cancer Res, 51: 3131-3135; Luo et al., 1997, Endocrinology, 138: 4435-4444). Combined treatment of DHEA and Acolbifene has been proposed as a beneficial chemopreventive and therapeutic approach in breast cancer (Labrie, 2001, Ref Gynecol Obstet, 8: 317-322). In fact, the inhibitory effect of DHEA on the growth of human breast cancer xenografts in nude mice supports its use as hormone replacement therapy (Dauvois et al., 1991, Cancer Res, 51: 3131-3135; Couillard et al., 1998, J Natl Cancer Inst, 90: 772-778).
WO 99/63974 disclosed medical uses of a selective estrogen receptor modulator in combination with sex steroid precursors